ruminant nutrition 1 - grass and forages

How many litres is the rumen in an adult sheep?

10-15

How many litres is the rumen in an adult cattle ?

150-200 litres

How much water does the rumen contain?

850-930g/kg water

what type of environment is the rumen?

Anaerobic

true or false: in cattle there is usually a caudal mat of fibre

True

each mL contains;

10^9 to 10^10 bacteria

10^6 protozoa

10^3 to 10^5 fungi

True or false?

True

True or false: there are as many bacteria in 1mL of rumen fluid as people on the planet

True

What are the evolutionary features of the rumen?

Bacteria and fungi enzymatically break down B-glycosidic linkages in fibre under anaerobic conditions

Rumen bacteria break down most of the protein in the rumen to ammonia, which they use to synthesise their own amino acids

what does fermentation of sugars, starch and fibre in the rumen produce ?

Short chain, “volatile” fatty acids (acetate, propionate and butyrate), as well as methane

Excess ammonia in the rumen is absorbed and converted to urea in liver, what happens after this ?

The urea can be recycled to the rumen via saliva or the rumen epithelium, or excreted in urine

What are the common forages?

Grass, grass silage , maize silage, whole crop wheat, hay, straw, kale/rape/fodder/beet/turnips

What are the concentrates ?

Cereals (barley, wheat, oats), by-products (sugar beet pulp, soya hulls), protein (soyabean meal, rapeseed meal), minerals/vitamins

What can concentrates be used for ?

Can be ground and mixed and pelleted to form a concentrate pellet (or cake )

All ruminant nutrition is undertaken on a _____ ____ basis ?

Dry matter

What does this table tell you?

That there is large variation in the dry matter content of ruminant forages

How to work out crude protein?

Nitrogen x 6.25

Why is there a large range of crude protein in grass/grass silage ?

Large range due to stage of maturity

Is there a big range in crude protein for maize silage/whole crop cereals ?

No, there is a lesser range

Are legume forages high or low in crude protein?

High (mean of 180-220g CP/kg DM)

How is fibre measured in forages?

Neutral detergent fibre (NDF)

What is NDF made up of ?

Cellulose + hemicellulose + lignin

true or false: NDF content does not indicate how lignified the fibre is

True

What does more nature grass mean about lignification ?

More mature grass is more lignified

which has less lignin in the fibre ; dicotyledons or monocotylendous plants ?

Dicotylendous plants

what does ME stand for? And what units is it measured in?

Metabolisable energy (megajoules/kg DM)

what does the total energy in feed =? And what is important to note about this ?

Gross energy

Not all is available to the animal

What is the ME equation?

ME = gross energy - faecal energy - urinary energy - methane energy

What would be the ME here ?

ME= 19 - 7.1 - 0.6 - 1.3 = 10.0 MJ/kg DM

How does lignin prevent bacteria from adhering to fibre ?

Lignin coats the outside of fibre

What can we learn from this table ?

Animal requirements are calculated on an ME basis

How can excvsss grass growth be conserved?

As hay or silage and fed when grass growth is below requirements

What grazing systems are there ?

Set-stocking

Rotational

Strip grazing

Zero grazing (or cut and carry)

Out wintering sheep and cattle (feeding forages over winter)

What grazing system is this ?

Continuous grazing or set stocking

What grazing system is this ?

Paddock or rotational grazing

What grazing system is this ?

Strip grazing

What grazing system is this ?

Forward or creep grazing

What are some health issues with grazing?

Bloat (especially if pasture clover content is high)

Nitrate poisoning

Intestinal parasites (“clean grazing”)

Liver fluke

Clostridial diseases (e.g. pulpy kidney, black leg)

Mineral deficiency

What are some mineral deficiency’s that can be caused from grazing?

Magnesium (staggers/tetany)

Calcium (hypocalcaemia: milk fever)

Copper (swayback)

Colbalt (pine)

What grazing system is used for ewes, store lambs, beef and dairy heifers and cows between September and march?

Outwintering

What are advantages of outwintering?

Less building (capital) and fewer respiratory problems

What is a major forage that is grazed?

Grass (deferred grazing)

What are some forages that are specifically grown?

Stubble turnips

Turnips

Kale

Forage rape

Forage rape/kale hybrid

Fodder beet

What are the two ways lambs can be “stored” and grown? (Depending on herbage allowance )

Slowly (e.g. 50g/d) to finish late winter

Or rapidly (250g/d) and finish earlier

How much of the dry matter intake do beef and dairy cattle usually provide ?

1/3 a big bale silage placed in field

What are cattle growth rates?

0.6-1.2 kg/d but can be variable

How to provide a dry bed?

Field selection, run back or provision of straw bedded area

There is a lower critical temperature from studies with suckler cows , what is it acclimatised (still, dry) and unacclimatised (windy, wet)?

Acclimatised = -18 degrees

Unacclimatised = + 7 degrees

What are some health issues when outwintering?

Photosensitisation

Nitrate poisoning

Kale anaemia factor

CCN

goitre

Bloat

Mineral deficiency

When do you get nitrate poisoning when outwintering?

Particularly when crop is growing quickly following fertiliser or overcast. Symptoms include muscle tremor, drooling and death

What animals are most susceptible to photosensitisation when outwintering?

In sheep and cattle grazing brassicas, particularly young cattle with white hair

What is kale anaemia factor caused by when outwintering?

Due to the amino acid S-methyl cysteine sulphoxude (SMCO) which causes anaemia and aperture loss

What causes CCN while outwintering?

Due to degradation of vitamin B1 in the rumen following dietary change, results in blindness, uncoordination, head held back.

What causes goitre when outwintering?

Kale is low in iodine, and high in goitrogejs, resulting in swollen thyroid gland , reduced fertility and still births

What causes bloat when outwintering?

Fodder beet and kale are very high in sugars and can reduce rumen PH

What mineral deficiency’s are caused in outwintering?

Copper, colbalt, selenium and iodine

What are the main methods of feed preservation?

Drying, ensiling, alkaline treatment, crimping and addition of an organic acid

What is drying hay made up of ?

Variety of grasses e.g. ryegrass, Timothy, bro,e. Fescue, clover (or mixtures)

How long is drying hay cut and left to airdry in the field ?

4-5 days , turning occasionally (weather dependent)

when is hay baled?

At around 850g DM/kg

Why is grass left?

To become mature (stemmier and higher in DNF than grass)

Grass can also be artificial dried then _____ ?

Pelleted

What are some health issues with hay?

Spontaneous combustion

Moulds such as fescue poisoning in tall fescue grass caused by an endophyte fungus

Affects ears, tail and cause lameness and reduced performance in cattle and sheep

Mould spores resulting in bovine allergic pneumonitis

Botulism, associated with dead birds or rodents in the hay bale, or if pasture fertilised with chicken litter

To feed the cow/sheep you have to feed the ______

Rumen

When are mould and mycotoxins health challenges with hay?

If it’s poorly dried

outwintering is undertaken to reduce costs but has what issues?

Health

What does a large range of dry matter and nutritive content of forages depend on?

Species

Stage of maturity at harvest

Degree of wilting

What is TMR?

Total mixed ration